Two UV organic-inorganic hybrid antimony-based materials with superior optical performance derived from cation-anion synergetic interactions

Finding suitable strategies to effectively enhance the optical properties of materials are the goal being pursued by researchers. Herein, cation-anion synergetic interactions strategy was proposed to develop two novel organic-inorganic hybrid antimony-based optical materials , (C 3 H 5 N 2 )SbF 2 SO 4 ( I ) and (C 5 H 6 N)SbF 2 SO 4 ( II ), which were obtained by introducing Sb 3+ cation containing stereochemically active lone-pair (SCALP) and organic π -conjugated cations into sulphate system. The synergistic interactions of the organic π -conjugated cations, the inorganic [SbO 2 F 2 ] 3− seesaw anions and the [SO 4 ] 2− distorted tetrahedra anions make their ultraviolet (UV) absorption edges approach 297 and 283 nm, respectively, and raise their birefringence up to 0.193@546 nm and 0.179@546 nm, respectively. Interestingly, although the two compounds have the same stoichiometric ratio and similar one-dimensional (1D) chain structure, they show opposite macroscopic symmetry, where the NCS compound ( II ) exhibits a large second-harmonic generation (SHG) response (1.6 times that of KH 2 PO 4 ). The two reported compounds are found to be promising UV optical materials in the experimental tests.